<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id='box1'>
        <div id='box2'>11</div>
    </div>
    <div id='box3'>11</div>
    <script>
        box11=document.querySelector('#box1');
        box2=box11.childNodes;//所有子节点box2=box11.children[0];
        box3=box11.nextElementSibling;//下一个兄弟节点
        //添加节点
        var h2=document.createElement('h2');
        h2.innerHTML='标题';
        box11.appendChild(h2);

        //插入节点
        box11.insertBefore(h2,box11.children[0]);

        //删除节点
        box11.removeChile(div.nextElementSibling);

        //克隆节点
        box11.appendChild(box11.children[0].cloneNone(1));

    </script>
</body>
</html>